User interactive systems interact with their users via bi-directional communication with the users. User interactive systems may include voice response systems in which the bi-directional communication is carried out by voice communication, i.e., the user speaks to the interactive system and the user interactive system also responds by a voice prompt. Examples of user interactive systems include navigation systems used in an automobile where the user asks for directions to a particular location by voice or by typing in a destination address and the navigation system responds by displaying the directions to the user along with voice instructions corresponding to the directions. Other examples include on-board computers used in automobiles to control the various functionalities (audio, air conditioning, etc.) of the automobile based upon interaction with the user. For example, the user may control the air conditioning in the automobile by interacting with the on-board computer by voice. The user interactive system in an automobile is sometimes called a “virtual passenger,” since they interact with the drivers as if another passenger were present in the vehicle.
Conventional user interactive systems typically use the same tone or content of the voice prompt when they interact with the users. For example, when a conventional vehicle navigation system gives directions to a destination to a user, it will use the same tone (e.g., high tone or subdued tone) and same content (e.g., “Turn right at third street.”) regardless of the user's state or driver's state, such as emotional states (happy, sad, excited, and the like) or other states (alert, drowsy, in a hurry, and the like). However, studies have shown that the interactive systems cannot communicate effectively with the users if they use the same tone or content of the voice prompt in their interaction with the users regardless of the user's state. Some conventional user interactive systems may change the voice (actor, dialect, etc.) manually by the user choice, but they cannot adjust their voice prompts automatically by detecting the user's state.
Therefore, there is a need for a method and system for determining the user's state in an interactive system. There is also a need for a method and system for adjusting or pausing the voice prompt of the interactive system based upon the determined user's state, especially in a voice response system, so that more effective interaction with the user may be accomplished.